Polymeric hydridosilazanes, processes for the preparation thereof, silicon nitride-containing ceramic materials which can be prepared therefrom, and the preparation thereof

Abstract

The invention relates to novel polymeric hydridosilazanes, their preparation, their conversion into silicon nitride-containing ceramic material, and this material itself. To prepare the polymeric hydridosilazanes, polymeric hydridothiosilazanes are reacted with NH 3 . To prepare the silicon nitride-containing ceramic material, the polymeric hydridosilazanes are then pyrolyzed.

We claim: 
     
       1. A process for the preparation of a ceramic material, which comprises pyrolyzing a polymeric hydridosilazane of the formula ##STR9## in which R is C 1  -C 6  -alkyl or C 2  -C 6  -alkenyl and x and y denote the molar fractions of the two structural units, and x+y=1, in an inert atmosphere at 800° to 1,400° C. 
     
     
       2. A process for the preparation of silicon nitride-containing ceramic material, which comprises pyrolyzing a polymeric hydridosilazane as claimed in claim 1 in an NH 3  atmosphere at 800° to 1400° C. 
     
     
       3. The process as claimed in claim 1, wherein, in order to produce silicon nitride-containing ceramic fibers, the polymeric hydridosilazane is initially dissolved in an organic solvent, and fibers are drawn from this solution and pyrolyzed after evaporation of the solvent. 
     
     
       4. The process as claimed in claim 1, wherein, in order to produce silicon nitride-containing ceramic shaped articles, the pulverulent polymeric hydridosilazane is pressed to form shaped articles before pyrolysis. 
     
     
       5. The process as claimed in claim 1, wherein, in order to produce silicon nitride-containing ceramic coatings, the polymeric hydridosilazane is initially dissolved in an organic solvent, and a coating is produced using this solution and pyrolyzed after evaporation of the solvent. 
     
     
       6. The process as claimed in claim 1, wherein the pyrolysis is carried out at 800° to 1200° C. 
     
     
       7. The process as claimed in claim 1, wherein the pyrolysis is carried out at 1200° to 1400° C. PG,16 
     
     
       8. Silicon nitride-containing ceramic material obtainable by the process as claimed in claim 1.